76 
Journal of Agricultural Research 
Vol. XXV, No. 2 
Current-season symptoms appeared in some of the cages in which the 
disease present was curly dwarf (inoculation Series i and 2, Table XVI) 
and in one of the cages in which the disease was mosaic (No. 14), resulting 
in mosaic in the upper leaves. Mosaic also resulted from No. 12 in which 
the symptoms were dwarfing, chlorosis, rugosity, and burning, from 
No. 11 in which there were dwarfing, brittleness, rugosity, and burning, 
and from No. 7 in which there were dwarfing, leaf dropping, and premature 
death. However, in No. 11 the final effect was mosaic-dwarf, and in 
No. 7 it was a combination of mosaic and streaking. Inoculation was 
effective in the Irish Cobblers only in No. 11 and 7, the results being 
similar to those in the other variety except for the absence of mosaic in 
No. 7. 
The second generation was planted in the open field and the symptoms 
are also given in Table XVI except that all the inoculated Irish Cobblers 
were spindling tuber and likewise the controls in this variety. The 
Green Mountain controls were all healthy. It appears that the inocula¬ 
tion of Green Mountains resulted in the transmission of leaf-rolling mosaic 
in No. 1, 2 (PI. 2, C, i,), and 3, from curly dwarf Rurals; of rugose 
mosaic in No. 7 from dwarfed seedling variety 39496 (PI. 4, A); of spindling- 
tuber disease in No. 5, 8 (PI. 3, B, 1) and 13 from spindling-tuber Green 
Mountains and Irish Cobblers; of mild mosaic in No. 5 from mild mosaic 
Green Mountains; of unmottled curly dwarf in No. 4 from Irish Cobblers 
(PI. 10, A, 2,) and of various combinations of these four diseases in No. 8 
(PI. 3, B),^ 11, 12, and 14 (PI. 8, B). It is noteworthy that with earlier 
transmission and consequent more current-season symptoms in 1921, 
there was more complete infection of the progeny in 1922. Infection of 
the Irish Cobblers, already spindling tuber, was not so apparently suc¬ 
cessful. In inoculations No. 1, 2, 3, 4, 7, and 12, the leaf-rolling mosaic, 
rugose mosaic, or unmottled curly dwarf symptoms induced in the 
Green Mountains were not like the symptoms in the source of inoculum 
hills or their progeny, suggesting varietal modification and masking of 
symptoms, especially of mosaic (PI. 2, C; 4, A). The inoculated hills 
in No. 7, the parents of the diseased hills in No. 10 and 14, and the 
Charles Downing diseased hill in No. 13, showed streaking which was 
replaced in the following generations by rugose mosaic or by mild mosaic 
in combination with spindling-tuber disease. 
INOCULATIONS PERFORMED IN 1922 
In the field, during 1922, leaf-mutilation inoculations with different 
types of mosaic, with leaf roll, and with spindling tuber were made on 
plants of the Green Mountain, Irish Cobbler, Bliss Triumph, and Rural 
New Yorker varieties. The method of planting, in 4-hill tuber units, 
resembled that of previous seasons. One or two hills in a tuber unit, 
either the second and third hill, or the third hill alone, were treated so 
that two or three uninoculated controls were in each inoculated tuber 
unit. Single applications were made in each series with the exception of 
Series 58, 59, and 60, in which the second hill in each unit received two 
inoculations, and with the exception of mild mosaic and leaf roll, where 
three repeated applications were made. The positive current-season 
results of these inoculations are presented in Table XVII. 
Inoculations with mild mosaic and leaf roll are not indicated in this 
table, since no current-season symptoms appeared. Infection from 
inoculations made under cages with mild mosaic by leaf mutilation is 
described in Table XVIII. Inoculations with spindling tuber were dis¬ 
cussed in Table VII. 
